Lubricating grease compositions



United States Patent 6 LUBRICATING GREASE COMPOSITIONS Philippe Bidault, Gruchet-le-Valasse, and Robert Metenier, Notre-Dame-de-Gravenchon, France, assignors to Esso Standard Societe Anonyme Francaise, formerly Standard Francaise des Petroles, a body corporate, Paris, France No Drawing. Application June 30, 1955 Serial No. 519,232

Claims priority, application France July 9, 1954 6 Claims. (Cl. 25242.1)

The present invention relates to improved lubricating greases, and particularly relates to lubricating greases of improved stability at high temperatures and under the influence of mechanical working, and which in addition have improved odour and colour. The invention particularly relates to lubricating greases containing a small stabilizing proportion of the condensation product of an alkylene oxide with an aromatic-amine or amide.

It is well known that in certain uses of greases, for instance in the lubrication of ball or roller bearings operating at high speed or under high stresses, few greases retain their consistency and their structure. Under these conditions rapid heating of the bearings occurs, resulting in breakdown of the grease structure.

It is well known that the lubricating properties of greases depend mainly on the properties of the oil from which the grease is obtained. The heating of the bearing, for instance, will be less if the oil possesses a suitable viscosity with a highviscosity index, at the temperatures at which it is used. It is generally considered desirable to use lubricating greases based on oils of a high viscosity index.

If paraflinic oils are used in the preparation of greases with an alkali metal soap base, particularly sodium greases, it is very diflicult to avoid the separation of the soap from the oil and to obtain stable greases, even with very slow cooling during their preparation. If the grease is cooled rapidly, for example by pouring the liquefied grease above its pour points and a thin layer on the plates, a considerable degree of sweating will take place together with separation of practically all the soap from the oil. This effect is less pronounced if naphthenic mineral oils are used. However the degree of sweating during storage or working may generally be reduced by adding certain compounds such as naphthenates or sodium aralalkylsulphonates. The specification of US. Serial No. 372,179, now US. Patent No. 2,854,410 describes and claims processes for preparing stable greases by adding to greases, particularly to alkali soap base greases, a stabilising proportion of the amide in which at least one valency of the nitrogen atom is linked to an alcohol group, the said amide being the amide of a fatty acid derived from a fatty material having 10 to 24 carbon atoms per molecule.

When using such greases however, it is desirable to incorporate phenyl a-naphthylamine or other well known oxidation inhibitors in the greases. However, the addition of such anti-oxidising agents results in adverse colouring of the grease, for instance instead of being a creamy yellow, the greases have a dark brown colour, and greases containing such anti-oxidising agents are further adversely affected in that they have unpleasant and characteristic odours.

The present invention relates to processes for preparing improved greases, which in addition to possessing good stability at high temperatures and when under mechanical stress possessed by the greases of copending application S.N. 372,179, are also resistant to oxidation, and do ice not require a further addition of conventional anti-oxidants, and which do not possess adverse colouring or obnoxious odours.

The combined stabilising and anti-oxidant compounds suitable for the purpose of the present invention are the condensation products of alkylene oxides or polyoxyalkylenes and aromatic amines or amides, such as phenyl a-naphthylamine, phenyl B-naphthylamine, diphenylamine benzamide, and also aralalkylene primary or secondary amines.

The alkylene oxide to be reacted with the aromatic amines or amides are oxides of ethylene, propylene, butylene, etc., or the corresponding poly-oxides. The mo lecular weight of the condensaiton products employed as the combined stabilising and anti-oxidising additives of the present invention may have molecular weights varying from about 300 to about 5000, depending on the number of molecules of oxide which are incorporated in the. final molecule. Thus the term alkylene oxide may be expressed by the general formula (CH CH O),,, where :1 may be any integer between 2 and 65.

The condensation products derived from aromatic amines may be represented by the general formula RNR-- CH CH O ,,CH CH OH and from amides by the general formula RCO--NR' CH CH O -CH CH OH wherein R is an aryl or an alkaryl group containing from 1 to 3 benzene rings, and R is asimilar group or an alkyl group or hydrogen, and x is an integer of from 1 to 64.

The lubricating oils used in the greases of the present invention may be normal or of synthetic origin, with viscosities which may vary from 80 to 3,000 SUS at 100 F., and preferably from about 90 to about 1000 SUS at 1000 F.

The viscosity index of the oils may range from 0 to 160, and is preferably higher than 60.

The soaps to be dispersed in the lubricating oil to form the grease of the present invention are preferably alkali metalsoaps, and particularly soaps of sodium and lithium, which tend to form greases with a sufficiently high pour point. They may be present in the grease in proportions of 330% by weight of total grease, depending on the final characteristics it is desired to obtain. The

fatty materials to be saponified to obtain the soaps are preferably saturated or unsaturated fatty acids. The fats themselves, such as triglycerides, may likewise be used, as well asthe fatty acids obtained from hydrogenated animal, marine or vegetable oils or fats or those obtained by the oxidation of hydrocarbons, such fatty acids having a number of carbon atoms ranging from 8-40 per molecule.

The combined stabiliser and anti-oxidant e.g. the condensation product of ethylene oxide with aromatic amines or amides, may be incorporated in the grease in proportions from .1 to 5% by weight, preferably from .1 to 2% by weight based on the final computation.

The grease according .to the present invention may be obtained in the usual process of mixing, heating and cooling, thus the fatty acid and condensation products described above, are added to all or part of the selected After heating to a temperature sufficient to obtain a homogeneous mixture, a saponifying agent is added and heating is continued until the mixture is completely dehydrated and melted. The grease is then poured in pans and after cooling the cakes of grease formed are worked to the desired consistency.

The condensation agents may be added at the end of cooking and before pouring of the grease. In the following examples the same basic grease has been used.

. 3 The composition of this basic grease is as. follows:

Percent Stearic acid l5 Caustic soda g Y V 2 .45 Mineral oil (150 SUS 100 F., VI 1'15) 82.55

Pour point F 3 70- Worked consistency:

60 strokes 193 1000 strokes 226 100,000 strokes 308 Bleeding test 1 (50 hours. at 212 F.) .perc ent 0.4 Oxidation test (Norma Hofimann test) hours 400 1 Bleeding test 100 gr. grease are placed on a cone of metal cloth with mesh aperture of 0.149 mm. (100 mesh),. placed above a beaker and kept for 50 hours in a drying closet at 112 The amount of oil bled is weighed at the end of ie tes Oxidation test (Norma Hoffmann test). A sample'of 12 g. rease is placed in a bomb at an oxygen pressure of 7 kg. sq; cm. art-210 F. The time-taken to'obtrain a= pressure drop of 0.35 kg. sq. cm. is measured.

Example 2 The additive employed was obtained by condensing 2' molecules of ethylene oxide with diphenyl amine.

The composition used is as follows:

Percent by'weight Stearic acid 15 Pure NaOH 2.45 Mineral oil of viscosity 150' SUS at 100" F.

viscosity index 115 81.5

Additive 1' The following characteristics were obtainedfor the grease of'this composition:

Pour point 'F 360* Consistency AS'FM:

60 strokes 280 100,000 strokes 317 Oxidation test (NormaHoffmann test) hour s" 500 Colour White; stabl'ein air. Odour Nil. Bleeding test (50 hours at-212'F.) ....percent;. 0.6

The grease obtained in the above examples possesses all the desired properties, i.e. stability and resistance and oxidation. They have a creamy white colour that is more attractive than the grease obtained by the separate addition of anti-oxidants such as phenyl a-naphthylamine, and in addition" they have no unpleaseant odour.

It is of course obvious that the above examples are for the purpose of illustrations and in no sense restricted to the present invention.

What is claimed is:

1. A lubricating grease comprising a major proportion of a lubricating oil, a minor grease making proportion of an alkali-metal soap-base grease-thickener, and contain ing in the range of 0.1 to 5.0 weight percent of the condensation product of an aromatic amine having in the range of 1 to 3 benzene rings and an alkylene oxide having in the range of 2 to 4 carbon atoms per molecule, said condensation product having a molecular weight in the'range of 300 to'5000;

2. A lubricating grease in accordance with claim 1 wherein said lubricating oil has a viscosity in the range of- 90-to 1000 seconds at 100 F. and aviscosity index in the range of to 160.

3. A lubricating grease in accordance with claim 1 wherein said alkylene oxide'is ethyl oxide.

4. A lubricating grease in accordance with claim 1 wherein said aromatic amine is phenyl naphthyla'mine.

5 A- lubricating grease-in accordance with claim 1 whereinsaid aromatic amine is diphenyl amine;

6. A- lubricating grease comprising a major proportion of a lubricating oil having a viscosity inthe range of to 1000 SUS at- F. and a viscosity index in the range of 60 to containing in the range of 3 to 30 weight percent ofa grease making alkali-metal soap of a high molecular weight fatty acid and the range of 0.1 to- 5 weight percent of a condensation product having the general formula- R-NR"'( cn crr o' -'-'CI-I CH OH wherein R and R are aryl groups containing in the range of l to 3 benzene rings and x is an integer from 1 to 64, the molecular weight of said condensation product being in the range of 300 to5000:

References Cited in the file of this patent UNITED STATES PATENTS 2,085,706 Schoelleret al. June-29, 1937 2,403,067 Fischer et al. July 2', 1946 2,475,589 Bondi July 12, 1949 2,545,190 Bondi= -Mar. 13, 1951 2,690,426 Jeiferson'et all Sept. 28 1954' OTHER REFERENCES Ethomeens Ethomids Ethofats, Armour and Co., 1949. 

1. A LUBRICATING GREASE COMPRISINGA MAJOR PROPORTION OF A LUBRICATING OIL, A MINOR GREASE MAKING PROPORTION OF AN ALKALI-METAL SOAP-BASE GREASE-THICKENER, AND CONTAINING IN THE RANGE OF O.1 TO 5.0 WEIGHT PERCENT OF THE CONDENSATION PRODUCT OF AN AROMATIC AMINE HAVING IN THE RANGE OF 1 TO 3 BENZENE RINGS AND AN ALKYLENE OXIDE HAVING IN THE RANGE OF 2 TO 4 CARBON ATOMS PER MOLECULE, SAID CONDENSATION PRODUCT HAVING A MOLECULAR WEIGHT IN THE RANGE OF 300 TO
 5000. 